This section provides information helpful in understanding the invention but that is not necessarily prior art.
Rink, U.S. Pat. No. 6,515,192, issued Feb. 4, 2003, discloses hyperbranched compounds having a tetrafunctional central group of the general formula C[-Aq-X-]m[-Ar-X-]n[-As-X-]o[-At-X-], in which m+n+o+p=4, m=an integer from 1 to 3 and n, o and p=0 or an integer from 1 to 3; q, r, s and t=an integer from 1 to 5, where q>r, s and t; X═—O—, —S— or A=—CR2-; where R═—H, —F, —Cl, —Br, —CN, —NO2, C1 to C3 alkyl or C1 to C3 haloalkyl or C1 to C3 alkoxy radical or, if q, r, s and/or t=at least 2, a C2 to C4 alkanediyl and/or C2-C4 oxaalkanediyl radical which bridges 2 to 5 carbon atoms, and/or an oxygen atom —O—, which bridges 3 to 5 carbon atoms, of the radical -A-.
Ramesh, U.S. Pat. No. 6,569,956, issued May 27, 2003, discloses a hyperbranched polyester polyol macromolecule having a plurality of both embedded and exterior hydroxyl groups. The hyperbranched polyol includes a central nucleus, a first chain extension, an intermediate substituent and a second chain extension. The central nucleus is a hydrocarbon structure with a plurality of oxygen atoms. The first chain extender is attached to the central nucleus and includes a carboxylic ester group and a plurality of hydroxyl groups. The intermediate substituent is attached to the first chain extender and is a polyfunctional carboxylic acid or anhydride. The preferred intermediate substituent is a cyclic compound. The second chain extension is attached to the intermediate substituent. The preferred second chain extension includes a glycidyl ester or epoxy. Also disclosed are coating compositions in which the hyperbranched polyol is reacted with an aminoplast or with an isocyanate.
Ramesh, U.S. Pat. No. 6,646,049, issued Nov. 11, 2003 discloses a binder for a coating composition with a principal resin polyol in combination with a hyper-branched polyol as a reactive intermediate and at least one crosslinker. The principal resin polyol is at least one of a polyester polyol, a polyether polyol, and a polyacrylate. Hyper-branched polyester polyols may be used as reactive diluents, which will cross-link with isocyanates, isocyanurates, epoxides, anhydrides or their corresponding polyacids and/or aminoplasts to form a binder having particular properties, to help control the rheology of a coating system. The hyperbranched polyol, the principal resin polyol, or both may, optionally, include a carbamate functional group. Coating compositions may be made using the binders together with additional components.
Ramesh et al., U.S. Pat. No. 6,861,150 issued Mar. 1, 2005 discloses a rheology control agent for a coating composition that is the reaction product of a first compound comprising a plurality of hydroxyl groups, of a lactone compound, and of a carbamate compound.
Ramesh et al., U.S. Pat. No. 7,226,971, issued Jun. 5, 2007, discloses a polyester resin for use in a coating composition. The polyester resin is the reaction product of a first compound comprising a plurality of hydroxyl groups, a lactone compound, a carboxylic acid anhydride, an epoxy compound having at least one epoxy group, and a carbamate compound.
Bruchmann et al., U.S. Pat. No. 7,858,733, issued Dec. 28, 2010, discloses high-functionality highly branched or hyperbranched polyesters based on di-, tri- or polycarboxylic acids and di-, tri- or polyols, processes for preparing them, and their use in coatings. The high-functionality highly branched or hyperbranched polyesters have a molecular weight Mn of at least 500 g/mol and a polydispersity Mw/Mn of 1.2-50, obtainable by reacting at least one aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid (A2) or derivatives thereof and at least one divalent aliphatic, cycloaliphatic, araliphatic, or aromatic alcohol (B2), containing 2 OH groups, with either a) at least one x-valent aliphatic, cycloaliphatic, araliphatic or aromatic alcohol (Cx) containing more than two OH groups, x being a number greater than 2, preferably between 3 and 8, particularly preferably between 3 and 6, more preferably from 3 to 4 and in particular 3 or b) at least one aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acid (Dy) or derivatives thereof containing more than two acid groups, y being a number greater than 2, preferably between 3 and 8, more preferably between 3 and 6, very preferably from 3 to 4 and in particular 3, in each case in the presence if appropriate of further functionalized building blocks E and c) subsequently reacting the product, if appropriate, with a monocarboxylic acid F, and the ratio of the reactive groups in the reaction mixture being chosen so as to set a molar ratio of OH groups to carboxyl groups or derivatives thereof of from 5:1 to 1:5, preferably from 4:1 to 1:4, more preferably from 3:1 to 1:3 and very preferably from 2:1 to 1:2.
It remains desirable to make further improvements in coating compositions containing hyperbranched polyols by using a more flexible, hyperbranched polyol that provides a coating layer with excellent properties and permits the coating composition to be made with a low content of volatile organic compounds.